The Chinese were the first to produce silk. The knowledge of doing it was kept as a big secret because silk was very expensive and the people who sold it got very rich.

Originally, the silk thread is made by a caterpillar. The most known butterfly producing silk is called Silk-Moth or bombyx mori (see photo, mating). The color of the silk depends on the species of butterfly making it.
The caterpillars spin the silk to protect them while they pupate. They spin one single thread which is about 2625 ft (800 m) long.

How did people get silk?
When the caterpillar finished spinning silk and was ready to pupate, it was thrown into hot water to be killed. If it had had the chance to get a butterfly it would have cut the valuable thread to get out. But people wanted to have one single long thread.

When the caterpillars were dead the thread was taken away from them. The water made this easier. Then the threads of different caterpillars were put together, rolled up and later used to make clothes and other things.

Silk on a pane of glass